Influence Of Post-slaughtering On Gel Characteristics And Tenderness Of Pork Muscle

With the improvement of consumption level and strengthen of nutrition value and health care function, the demand on meat quality is rigorous than before. Whether the production of restructured meat products and meat emulsion is successful mostly depends on functional properties of muscle protein, which is gelling property, water retention, associatively, emulsifying property and so on. In this thesis, effects of pH value, sodium chloride concentration and heating temperature on heat-induced gelation properties of pork homogenate from hind leg, effects of postmortem chilling time and following freezing of fresh pork on gelation properties of pork homogenate, effects of high pressure and holding time on gelation properties of pork homogenate and effects of postmortem chilling time on tenderness and related quality of pork were studied.1. Quadratic general rotary design was adopted to study effects of pH value, sodium chloride concentration and heating temperature on heat-induced gelation properties of pork homogenate from hind leg. The results showed that there existed diversity among the effects of different treatments on diverse characteristics of gels. The effects of pH value and sodium chloride concentration on hardness, springiness, cohesiveness, gumniness and chewiness of gclation were of basic agreement and existed obvious interaction. The optimization calculation showed that the optimum condition of the formation of gelation was pH6.33, sodium chloride concentration0.67M, and heating temperature of75℃2. Uniform experimental design was applied to examine the effects of postmortem chilling time and following freezing of fresh pork on gelation properties of pork homogenate. The results showed that there existed significant effect of postmortem chilling time and following freezing of fresh pork on protein concentration, dehydration rate, water retention, hardness, springiness, cohesiveness, gumminess, chewiness, resilience of gelation and gel strength and the effect existed obvious interaction. Protein concentration was decreased as the postmortem chilling time prolonged, while dehydration rate, water retention, cohesiveness, chewiness, resilience of gelation and gel strength were increased. Under the same postmortem chilling time, protein concentration, cohesiveness, and resilience of gelation were significantly lower after freezing treatment and water retention was higher. After freezing treatment, hardness, springiness and gumminess of gelation increases gradually as the postmortem chilling time prolonged and vice versa.3. Uniform experimental design was applied to examine the effects of high pressure and holding time on gelation properties of pork homogenate. The results showed that protein concentration of homogenate, dehydration rate and springiness of gelation were decreased as the pressure increased while gumminess of gelation was increased. As holding time prolonged, protein concentration of homogenate were decreased slowly, gumminess of gelation was increased rapidly, springiness of gelation decreased first and then increased while the trend of dehydration rate and hardness of gelation was opposite.4. Single factor design was adopted to study the effects of postmortem chilling time (1,4,8,12,16,20,24,36,48,60,72,96,120,144,168h) on tenderness and related quality of pork. The results showed that there were significant effects of postmortem chilling time on tenderness and related quality. As postmortem chilling time prolonged, the trend of L*value, a*value and cook loss was increased first and then decreased which was opposite to pH value. During16-168h postmortem shear force was decreased gradually. Myofibrillar fragmentation index was increased as postmortem chilling time prolonged and it was increased rapidly at16-72h.